GI tract transcription factor network. A plot of the relationships in expression among the complement of transcription factors (TFs) expressed in the porcine GI tract. TFs with similar expression profiles group together and groupings likely represent regulatory units that work together to control cellular differentiation within regions of the organ. A number of TFs have been selected that are expressed in a very region-specific manner but whose known biology has not previously been associated with a functional role within this organ. GI, gastrointestinal.